This invention relates to electronically steered phased array antennas, and in particular to those where the beam forming and shaping functions of the phased array antenna is performed by microwave phase shifters.
In electronically steered phased array antennas, where the beam forming and shaping functions is performed by microwave shifters, the shifters insert a given amount of path delay (phase shift) into each radiating element. The amount of the delay is a function of the beam pointing angle and the beam shape desired. A dedicated computational device, usually referred to as a beam steering controller computes the individual phase shift commands for each phase shifter and outputs this information to the phase shifter.
A phase shifter driver is located between the beam steering controller and each phase shifter. The phase shifter driver is a voltage level translation and power amplifier device which is used to generate the proper drive signals for the phase shifter itself. The phase shifter and phase shifter driver combination is sometimes referred to as a phase control module.
An advantage to electronically steered phased array antennas is that they can be calibrated, or tuned by adjusting the phase shift command of each phase control module. This calibration is needed to compensate for manufacturing variations such as the physical path length differences, phase controlled module insertion phase differences, phase shift variations due to temperature fluctuations, antenna mounting misalignment, and the like. These tuning correction factors are typically stored in the beam steering controller in a non-volatile memory. In operation they are used to modify the phase shift command to each phase control module so as to maintain the desired beam pointing direction and beam shape despite variations in the above mentioned parameters.
The storage of these parameters in the beam steering controller has caused significant configuration control problems with attendant lost time and increased cost. The reason for this is that once a beam steering controller has had a particular antenna's tuning parameters programmed into it, the beam steering controller is no longer a generic piece of hardware. The dedicated beam steering controller must always accompany the particular antenna, and cannot be used with another antenna until the beam steering controller is reprogrammed with that antenna's tuning parameters. Furthermore, at times, the data for the wrong antenna is programmed into the beam steering controller, causing degraded antenna performance.